Getting a Look At Web Services

Web services promise to be the next major frontier in computing. Up until the advent of Web services, interoperability and integration (the exchange of data among computer systems) were extremely limited or cumbersome. Prior to Web services, limited integration took place with numerous technologies, vendors, obstacles, and formats that prevented the sharing of data. Then Web service technology came along and changed all that.

What the heck are Web services?

Web services encompass the technology that's used in allowing data to be transmitted across the Internet by using a familiar programming methodology. Only data are transmitted using Web services technology; Web services do not have a visual interface, such as text boxes, radio buttons, and the like.

For example, a Web service may be offered in a B2B (business to business) scenario whereby Company A provides a currency conversion Web service and Company B, in turn, uses this Web service to provide the currency conversion functionality to its customers. The Web service offered by Company A can also be used by Company C in a different capacity. For example, Company C may combine Company A's Web service with other functionality and offer it as a Web service to other companies. In both scenarios, specific functionality is developed and made available as a programmable Web service that can be accessed by other companies over the Internet.

The term Web services means something different to each person, depending on his or her interest. Executives are likely to not understand exactly how the Web services technology can simplify development, but they are going to understand the high return on investment (ROI). Conversely, developers and architects will likely understand that the Web services technology can help shorten development time and drastically make connectivity easier, but they won't grasp the immediate benefits of high ROI. Typically, developers and architects simply want to implement the coolest solution and use the latest and greatest technologies.

Web services is a technology for transmitting data over the Internet and allowing programmatic access to that data using standard Internet protocols. The term Web service is not used to represent a company who simply offers services on the Web, such as a banking Web site. Although such a company offers a service over the Web, it doesn't necessarily make its service available by using a programmatic interface that allows two applications to be integrated. In fact, a Web service allows a developer to include functionality into a program without needing to "reinvent the wheel" and without needing to know anything about the business or complexity of the Web service that he or she is using.

What Web services can do for you

Web services is a broad term that represents all the technologies used to transmit data across a network by using standard Internet protocols, typically HyperText Transfer Protocol (HTTP). An eXtensible Markup Language (XML) format is used to represent the data, which is why Web services are sometimes known as XML Web services.

You can think of an individual Web service as a piece of software that performs a specific task (also known as a function), and makes that task available by exposing a set of operations that can be performed (known as methods or Web methods) with the task. Additionally, each of the methods exposes a set of variables that can accept data passed into the method. These variables are known as parameters or properties. Together, the properties and methods refer to a Web service's interface. For example, Company A creates a Web service that provides currency rate functionality, which may expose a method called GetRate. Company B is then able to pass a parameter called CountryCode into the GetRate method. The GetRate method takes the CountryCode parameter, looks up the appropriate currency rate in a database, and returns the rate back to the program that requested it.

In this example, which database did Company A use to access the currency rate information? What was the name of the database server? What communication mechanisms and security mechanisms were used to access the database server? The answer to all of these questions is, "It doesn't matter." The beauty of a Web service is the concept of encapsulation. Encapsulation allows the complexity of retrieving the actual currency rate to be completely self-contained within the company that created the Web service (Company A). The only thing that Company B knows is that they called a Web service to get a currency rate and it was given to them.

Web services are made possible by placing the programs, or applications, on a Web server, such as Microsoft Internet Information Server (IIS). Because the application resides on a Web server, it can be called, or invoked, from any other computer on the network by using HTTP. The Web service provides seamless distributed computing across the entire network, as long as both sides know how to use a Web service.

One major advantage of invoking or creating Web services over HTTP is that if the Web server is on the Internet, the network administrators on both ends of the data transmission don't have to open any additional ports in their firewalls. All transmission of data is sent across port 80 (typically) by using HTTP. Port 80 is always open in a firewall because it is the same port used to browse the Internet. The fact that the network administrators don't need to open additional ports means that you face virtually no additional security risk in using Web services.

Another major advantage in Web services is that (because Web services conform to open standards) a Web service written on one platform (such as the Microsoft platform) can call another Web service written on another platform (such as Linux).

Because of their innate flexibility, Web services make the notion of software as a service a real possibility. And because Web services provide integration between two systems, software as a service refers to the possibility of not having to install software on workstations or servers, but rather, being able to use it from across the Internet.

Web services can change the way you use all your computing resources by doing the following:

  • Save hassle: Imagine you need to install Microsoft Office. If Microsoft decides that they want to make Office available as a Web service, you don't have to go out, purchase the software, and install it out of the box to all the computers in your network. Instead, you can get the full functionality of that piece of software across a Web interface without any installation at all.
  • Save money: Imagine renting or leasing software instead of buying it. You can "break your lease" when and if the applications aren't working for your organization, which can save you lots of money.
  • Stay ahead of the game without even trying: Imagine not having to keep up-to-date with the latest version. The latest version is always available from the vendor who provides the software as a service.

What you're really doing when you use software as a service this way is outsourcingfunctions that you used to perform within your organization.

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